If you calculate based on the going price of gold, which is ~900 USD per ounce today, then it's ~ 30 Canadian dollars per gram (75% purity, exchange rate ~1.25 CDN = 1 USD, 28.3 g = 1 ounce).

This number is meaningless without a context. If you want to sell some old gold jewellery as scrap, the value can be about half that (~$15/gram), but if you are buying something that's made out of 18K gold you will have to pay much more than $30/gram. Whether gold is white or yellow really does not make a difference.

If you calculate based on the going price of gold, which is ~900 USD per ounce today, then it's ~ 30 Canadian dollars per gram (75% purity, exchange rate ~1.25 CDN = 1 USD, 28.3 g = 1 ounce).

This number is meaningless without a context. If you want to sell some old gold jewellery as scrap, the value can be about half that (~$15/gram), but if you are buying something that's made out of 18K gold you will have to pay much more than $30/gram. Whether gold is white or yellow really does not make a difference.

The price of finished jewellery depends heavily on the design, since you are paying not just for the gold but also for the labour. Whether you are getting a good deal on that necklace or not depends on how much similar necklaces cost from other jewellers and how much you actually like its design.

If you have a picture of that necklace, post it and I can see if what you're getting looks like a good price for it or not.

If you ever were to sell it back as scrap gold, you would only get a fraction of the cost back, similarly to how scrap cars don't cost nearly as much as new ones.